Don't convert scope variables to dict with name as key

That was only used for a fallback case in the expression widget.
It's cheaper to do it there if needed instead of doing it all the time.

lua/dap/entity.lua

@@ -1,9 +1,6 @@
 local utils = require('dap.utils')
 local M = {}
 
----@diagnostic disable-next-line: deprecated
-local islist = vim.islist or vim.tbl_islist
-
 
 local variable = {}
 M.variable = variable
@@ -18,6 +15,7 @@ local syntax_mapping = {
 }
 
 
+---@param var dap.Variable|dap.EvaluateResponse
 function variable.get_key(var)
   return var.name or var.result
 end
@@ -28,6 +26,7 @@ function variable.is_lazy(var)
 end
 
 
+---@param var dap.Variable|dap.EvaluateResponse
 function variable.render_parent(var)
   if var.name then
     return variable.render_child(var, 0)
@@ -59,11 +58,7 @@ end
 ---@param var dap.Variable
 ---@result dap.Variable[]
 function variable.get_children(var)
-  if islist(var.variables) then
-    return var.variables
-  else
-    return var.variables and vim.tbl_values(var.variables) or {}
-  end
+  return var.variables or {}
 end
 
 

lua/dap/session.lua

@@ -770,18 +770,14 @@ function Session:_request_scopes(current_frame)
     end
     local scopes = scope_resp.scopes
     current_frame.scopes = scopes
-    local function toname(var)
-      return var.name
-    end
     for _, scope in ipairs(scopes) do
       if not scope.expensive then
 
         ---@param resp dap.VariableResponse?
         local function on_variables(_, resp)
-          if resp then
-            scope.variables = utils.to_dict(resp.variables, toname)
-          end
+          scope.variables = resp and resp.variables or nil
         end
+
         local varparams = { variablesReference = scope.variablesReference }
         self:request('variables', varparams, on_variables)
       end

lua/dap/ui/widgets.lua

@@ -355,55 +355,66 @@ M.sessions = {
 }
 
 
-M.expression = {
-  new_buf = new_buf,
-  before_open = function(view)
-    view.__expression = vim.fn.expand('<cexpr>')
-  end,
-  render = function(view, expr)
-    local session = require('dap').session()
-    local layer = view.layer()
-    if not session then
-      layer.render({'No active session'})
-      return
+do
+
+  ---@param scopes dap.Scope[]
+  ---@param expression string
+  ---@return dap.Variable?
+  local function find_var(scopes, expression)
+    for _, s in ipairs(scopes) do
+      for _, var in ipairs(s.variables or {}) do
+        if var.name == expression then
+          return var
+        end
+      end
     end
-    local expression = expr or view.__expression
-    local context = session.capabilities.supportsEvaluateForHovers and "hover" or "repl"
-    local args = {
-      expression = expression,
-      context = context
-    }
-    local frame = session.current_frame or {}
-    local variable
-    local scopes = frame.scopes or {}
-    session:evaluate(args, function(err, resp)
-      if err then
-        for _, s in pairs(scopes) do
-          variable = s.variables and s.variables[expression]
+    return nil
+  end
+
+  M.expression = {
+    new_buf = new_buf,
+    before_open = function(view)
+      view.__expression = vim.fn.expand('<cexpr>')
+    end,
+    render = function(view, expr)
+      local session = require('dap').session()
+      local layer = view.layer()
+      if not session then
+        layer.render({'No active session'})
+        return
+      end
+      local expression = expr or view.__expression
+      local context = session.capabilities.supportsEvaluateForHovers and "hover" or "repl"
+      local args = {
+        expression = expression,
+        context = context
+      }
+      local frame = session.current_frame or {}
+      local scopes = frame.scopes or {}
+      session:evaluate(args, function(err, resp)
+        if err then
+          local variable = find_var(scopes, expression)
           if variable then
-            break
+            local tree = ui.new_tree(require('dap.entity').variable.tree_spec)
+            tree.render(view.layer(), variable)
+          else
+            local msg = 'Cannot evaluate "'..expression..'"!'
+            layer.render({msg})
+          end
+        elseif resp and resp.result then
+          local attributes = (resp.presentationHint or {}).attributes or {}
+          if resp.variablesReference > 0 or vim.tbl_contains(attributes, "rawString") then
+            local tree = ui.new_tree(require('dap.entity').variable.tree_spec)
+            tree.render(layer, resp)
+          else
+            local lines = vim.split(resp.result, "\n", { plain = true })
+            layer.render(lines)
           end
         end
-        if variable then
-          local tree = ui.new_tree(require('dap.entity').variable.tree_spec)
-          tree.render(view.layer(), variable)
-        else
-          local msg = 'Cannot evaluate "'..expression..'"!'
-          layer.render({msg})
-        end
-      elseif resp and resp.result then
-        local attributes = (resp.presentationHint or {}).attributes or {}
-        if resp.variablesReference > 0 or vim.tbl_contains(attributes, "rawString") then
-          local tree = ui.new_tree(require('dap.entity').variable.tree_spec)
-          tree.render(layer, resp)
-        else
-          local lines = vim.split(resp.result, "\n", { plain = true })
-          layer.render(lines)
-        end
-      end
-    end)
-  end,
-}
+      end)
+    end,
+  }
+end
 
 
 function M.builder(widget)

lua/dap/utils.lua

@@ -20,7 +20,11 @@ end
 --  `get_key`   is used to get the key from an element of values
 --  `get_value` is used to set the value from an element of values and
 --               defaults to the full element
+---@deprecated
 function M.to_dict(values, get_key, get_value)
+  if vim.notify_once then
+    vim.notify_once("dap.utils.to_dict is deprecated for removal in nvim-dap 0.10.0")
+  end
   local rtn = {}
   get_value = get_value or function(v) return v end
   for _, v in pairs(values or {}) do